There are many applications in which an amount of a liquid solution is dispensed onto a specific area. These situations especially occur in the context of medical applications where sterile, non-preservative solutions are used and where the solution must be dispensed in discrete portions onto a specific area. These delivery systems usually consist of a storage or reservoir area and some form of delivery element. Often, as a solution is dispensed from the reservoir and through the delivery element some back flow of the solution may be returned into the storage reservoir. This back flow, having been exposed to the environment outside the storage reservoir, may contain particulate and/or bacterial contamination and thus creates a problem with sterile solutions, since the contaminates may be transmitted into the material stored in the storage reservoir. The sterility of the solution remaining in the storage reservoir may thus be jeopardized by this backflow of the solution returning to the solution remaining in the storage reservoir.
Product delivery systems for dispensing a liquid solution are well-known in the art. However, these product delivery systems have design characteristics that can be improved. For instance, some product delivery systems have openings which remain open to the atmosphere when not in use, thereby allowing particulate and/or bacterial contaminates to enter the solution remaining in storage. Further, some product delivery systems have valves that are not positive shut-off valves. These non-positive shut-off valves will allow low viscosity fluids to drip or discharge when at rest. Some other product delivery systems have storage reservoirs that preclude the product from being dispensed from the opening in the reservoir when an air bubble remains in the opening to the delivery tube.
Some other product delivery systems have shut-off valves that do not form a tight seal in a discharge tube. These shut-off valves may consist of two male parts that only pinch the delivery tube. Further, some product delivery systems must be operated with two hands of the user. Other product delivery systems further do not provide a constant pressure on the storage reservoir to provide a constant flow of product. Finally, some product delivery systems do not deliver a measured amount of product.
It will be appreciated from the foregoing that there is a definite need for an improved product delivery system. The present invention fulfills these needs.